Rubber compositions containing conjugated diene polymers such as polybutadiene and styrene-butadiene copolymers have been used in the prior art as rubber compositions for vehicle tires.
PTL 1 describes a modified rubber composition including a modified conjugated diene-based polymer obtained by reacting a diene-based polymer rubber having an alkali metal end or an alkali metal-added conjugated diene-based rubber, with a specific aminosilane compound having a dialkylamino group, for the purpose of improving the resilient elasticity and the low temperature JIS hardness.
PTL 2 describes a modified polymer rubber obtained by reacting an active polymer having an alkali metal end, with a specific aminosilane compound having a dimethylamino or diethylamino group, and a rubber composition containing the modified polymer rubber, for the purpose of improving the resilient elasticity.